Alright, you're going to argue that these aren't paperbacks at all, but
they were (with the exception of the first two books in the series, which were real leather).
They were the first inexpensive books sold in the United States. Published
by Albert Boni, Harry Scherman and Maxwell Sackheim, the run encompassed
101 books printed between 1920 and 1924. All were green, and measured 3¼
inches by 4 inches. The red books seen here were printed by the
follow-on company, Robert K. Haas, Inc. Both firms were in New York.

The books were sold in Woolworth's and
through ads in National Geographic magazine. In some cases, they were
given away free in cereal boxes and as other incentives.

The "fake leather" covers were murder
on the pages themselves ... or at least the front and back pages, which in
some cases have become so brittle and discolored that they are barely
readable. One other problem is that the covers overlapped the pages on all
three edges, and since most books have been stored upright, the bottom
edges are usually curled.

Some of the books were illustrated ...
a few profusely so, such as the book seen here on Mother Goose Rhymes.